Dimensioning an optical packet/burst switch — More interconnections or more delay lines?

We present performance evaluation of an optical packet/burst switch with internal fiber rings. Such a switch consists of multiple fabrics linked together by direct interconnections and optical delay lines. Having more number of optical delay lines and direct interconnections per fabric pair reduces contention and results in a reduced blocking probability. However, due to the size and cost of optical delay lines, it is desirable to minimize their number for a specific blocking probability. We propose an analytical model for the switch in order to study its scalability and packet/burst blocking probability. The switch is then dimensioned for given values of blocking probability and a given range of input load. Simulation results concerning switch scalability by taking into account the most relevant physical effects are also shown. We then consider the minimal practical switch size and discuss how the switch can be dimensioned with a combination of delay lines and direct interconnections to achieve our target of a certain blocking probability and range of input load using a minimum number of fiber delay lines.